Immunity

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Immunity
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Nonspecific Defense

• Skin and Mucous Membranes
• acid sweat pH 3?5
• enzyme in perspiration, tears, sweat, and saliva
• lysozymes - attacks bacterial cell walls
• respiratory tract contains cilia and mucus
• digestion - acid in the stomach

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Leukocytes

• neutrophils - chemotaxis - attracted by chemical
  signals
• self-destruct when destroying others
• few day life span
• monocytes - morph into macrophages longer lived
• amoeboid cells - ingest bacteria, viruses, and
  cell debris
• some bacteria have defenses to these
• eosinophils - cytoplasmic granules with enzymes
  used against invaders discharged
• mainly attack parasites (worms)
• natural killer cells - kill off infected cells of
  own body - very versatile in what attack
• recognize new/unusual proteins on the plasma
  membrane
• more rapid response than other cells
• may stop tumors and virus infestations
• poke hole in plasma membrane - proteins called
  perforins
• plasma cells - produce Ab that are in blood

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Antimicrobial Proteins

• complement - proteins that ID and dagger invaders
• interact with other defense mechanisms

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Antimicrobial Proteins

• interferon - virus infested cell (and activated
  lymphocytes and macrophages)
• releases substances that will improves nearby
  cell defenses
• increase protein production that inhibit viral
  replication
• especially for short term infection - cold and
  flu
• activates phagocytes

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Interferons
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Inflammatory Response - pain, heat and swelling

• damaged cells release prostaglandins, proteins,
  and K
• vasodilation increase blood supply
• histamines released (from mast cells or
  basophils) cause localized vasodilation
• prostaglandins also help this to happen
• heparin reduces clotting so new cells keep coming
  and cleansing
• later a clot forms to seal off and slow spread of
  pathogens
• increased temperature (increased blood flow) -
  activates/catalyzes enzymatic reactions of
  phagocytes
• may also denature foreign enzymes or proteins
• phagocytic cells migrate to area - via complement
  proteins and other factors
• 1st neutrophils activation - increased
  metabolic activity
• release H2O2 and nitric oxide to kill of
  pathogens
• invade then die
• macrophages remain to protect
• may get pus from dead cells and fluid during
  clean up
• severe infection ? systemic response
• bone marrow releases more neutrophils
• increase leukocytes
• fever - due to pathogens or proteins called
  pyrogens that re-set temp for battle

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Lymphatic System - tissues and free cells

• Cells T cells (thymus-dependent) cells, B cells
  (bone marrow derived) and Natural Killer cells
• lymph node lymph tissue wrapped in fibrous CT
• percolate out unwanted - capture cancer cells

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Temperature

• fever - stimulates phagocytosis
• inhibits microbial growth
• reduces Fe that bacteria need
• speeds up tissue repair

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Specific Response

• T Cells start in bone marrow ? thymus where
  mature
• Cell mediated response
• ID via antigens produced
• Several kinds of effector cells
• Helper - initiate humoral and cell mediated
  response
• stimulate activation of both T cells and B cells
• Cytotoxic - lyse cell infected w/ virus or cancer
• production of cell mediated immunity
• some serve as memory
• no response on first exposure, but many made
  for next time
• Natural Killer cells lymphocytes
• surveillance of cells
• attack foreign cells, viral infected cells and
  cancer cells
• Inducer development of T cells in thymus
• B Cells - bone marrow
• Humoral response or Ab response
• ID antigen and the start to reproduce --gt plasma
  cells ( effector cells)
• which secrete Abs that flag antigens for
  destruction

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Strategies

• Innate immunity - genetically determined
• people not susceptible to same diseases as gold
  fish
• Active immunity - after exposure to an antigen
• own immune system - has many capabilities these
  are stimulated after exposure
• Natural from infection - starts to develop after
  birth
• develops on an as needed basis
• Artificial (Induced) - deliberate exposure
• from vaccination/immunization
• and the forced version where your Mom forced
  you to play with the kid with chicken pox so you
  could develop immunity
• Passive immunity - Ab from one individual to
  another
• usually short lived
• example mother to fetus - across placenta, in
  milk
• can also be artificial (induced)

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Humoral response

• Ab immune response to toxins, bacteria, and
  viruses
• Ab production from lymphocytes, carried on B
  cells plasma membrane
• if antigens bind to Ab then the B cells are
  sensitized
• sensitized B cell encounter an already activated
  helper T cell
• B cells then usually --gt mitosis --gt plasma cells
  and memory B cells
• Memory B cells --gt 2nd exposure --gt mitosis

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Ab aid to destroy antigens

• Neutralize - land on specific site on pathogens
  needs to enter host cells

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Ab aid to destroy antigens

• Agglutination and precipitation - form bridges
  between two pathogen cells
• Ab can bind on two spots - tips of Y

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Ab aid to destroy antigens

• Activate complement - when bound to antigen
• change in shape so compliment proteins bind
• complements proteins that supplement the
  action of Abs
• destroy target cells plasma membrane - create a
  pore

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Ab aid to destroy antigens

• stimulate inflammation - basophils and mast cells
• attract phagocytes - neutrophils and macrophages
• makes target easier for macrophages to engulf
• gives phagocytes something to hang onto
• vs slick cell membrane of some bacteria
• Attract phagocytes - eosinophils, neutrophils,
  macrophages
• Prevents bacteria and viral adhesion
• makes it hard for pathogens to attach

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Cell mediated response

• attack viruses, abnormal cells, bacteria, fungi,
  protozoans, worms,
• transplant tissues, cancer cells
• T cell activation - before immune response must
  activate by exposure to antigen
• Major histocompatibility complex (MHC)
  glycoprotein self markers
• unique to each individual
• MHC Class I membranes of all nucleated cells,
  from golgi
• if abnormal peptides are present ? T cell
  activated
• common for viruses to bind here
• MHC Class II found only in Antigen presenting
  cells
• all monocytes/phagocytes microglia, in CT,
  in liver
• T cells are specific to an antigen - only
  activated to certain antigens
• Memory - based upon memory cells from 1st
  infection
• 1st immune response increase lymphocytes to
  form clones of effector cells
• 2nd immune response faster, Ab more effective
  at binding to antigen
• from second time infected